Data storage availability in the 1980s meant that we were not able to keep the multiple sources … only the station series after adjustment for homogeneity issues. We, therefore, do not hold the original raw data but only the value-added (i.e., quality controlled and homogenized) data.
Were they storing the data on floppy disk? People have been making backups of massive amounts of data across multiple tapes for decades.
This is not a big deal. We solved this back in the 1960s. You grab an IT guy, throw him at the problem and presto - multiple tapes, multiple copies. Store in a cool dry place. Good for decades.
 Which (duh) is a problem. Without the original data you're pretty much taking their word for things. Which ain't how I learned that Science was Done.